CN116463714A - Preparation of hexagonal Yb structure by optical floating zone method x In 1-x FeO 3 Method for growing single crystal - Google Patents
Preparation of hexagonal Yb structure by optical floating zone method x In 1-x FeO 3 Method for growing single crystal Download PDFInfo
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- 239000013078 crystal Substances 0.000 title claims abstract description 91
- 238000000034 method Methods 0.000 title claims abstract description 56
- 230000003287 optical effect Effects 0.000 title claims abstract description 20
- 238000002360 preparation method Methods 0.000 title claims description 9
- UQSXHKLRYXJYBZ-UHFFFAOYSA-N Iron oxide Chemical compound [Fe]=O UQSXHKLRYXJYBZ-UHFFFAOYSA-N 0.000 claims abstract description 110
- 239000002994 raw material Substances 0.000 claims abstract description 77
- 239000000463 material Substances 0.000 claims abstract description 35
- 238000005245 sintering Methods 0.000 claims abstract description 26
- 230000008569 process Effects 0.000 claims abstract description 17
- 238000002156 mixing Methods 0.000 claims abstract description 8
- UZLYXNNZYFBAQO-UHFFFAOYSA-N oxygen(2-);ytterbium(3+) Chemical compound [O-2].[O-2].[O-2].[Yb+3].[Yb+3] UZLYXNNZYFBAQO-UHFFFAOYSA-N 0.000 claims abstract description 6
- 229910003454 ytterbium oxide Inorganic materials 0.000 claims abstract description 6
- 229940075624 ytterbium oxide Drugs 0.000 claims abstract description 6
- 238000005056 compaction Methods 0.000 claims abstract description 4
- 229910003437 indium oxide Inorganic materials 0.000 claims abstract description 4
- PJXISJQVUVHSOJ-UHFFFAOYSA-N indium(iii) oxide Chemical compound [O-2].[O-2].[O-2].[In+3].[In+3] PJXISJQVUVHSOJ-UHFFFAOYSA-N 0.000 claims abstract description 4
- 238000005303 weighing Methods 0.000 claims abstract description 4
- 238000002844 melting Methods 0.000 claims description 25
- 230000008018 melting Effects 0.000 claims description 25
- 238000007599 discharging Methods 0.000 claims description 23
- 238000000498 ball milling Methods 0.000 claims description 19
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 claims description 13
- 229910052760 oxygen Inorganic materials 0.000 claims description 13
- 239000001301 oxygen Substances 0.000 claims description 13
- 238000000227 grinding Methods 0.000 claims description 8
- 238000007493 shaping process Methods 0.000 claims 1
- 238000001816 cooling Methods 0.000 abstract description 34
- XEEYBQQBJWHFJM-UHFFFAOYSA-N iron Substances [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 19
- 238000010438 heat treatment Methods 0.000 description 15
- 229910052761 rare earth metal Inorganic materials 0.000 description 12
- -1 Rare earth iron oxide Chemical class 0.000 description 7
- 235000013980 iron oxide Nutrition 0.000 description 7
- 238000005336 cracking Methods 0.000 description 6
- 238000002425 crystallisation Methods 0.000 description 6
- 230000008025 crystallization Effects 0.000 description 6
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 5
- 230000000052 comparative effect Effects 0.000 description 5
- 229910052736 halogen Inorganic materials 0.000 description 5
- 238000000462 isostatic pressing Methods 0.000 description 5
- 239000004570 mortar (masonry) Substances 0.000 description 5
- 150000002910 rare earth metals Chemical class 0.000 description 5
- 239000004744 fabric Substances 0.000 description 4
- 230000005291 magnetic effect Effects 0.000 description 4
- 229910000859 α-Fe Inorganic materials 0.000 description 4
- 230000008859 change Effects 0.000 description 3
- 238000002441 X-ray diffraction Methods 0.000 description 2
- 230000005290 antiferromagnetic effect Effects 0.000 description 2
- 239000012535 impurity Substances 0.000 description 2
- 230000003993 interaction Effects 0.000 description 2
- 229910052742 iron Inorganic materials 0.000 description 2
- 230000005302 magnetic ordering Effects 0.000 description 2
- 230000010287 polarization Effects 0.000 description 2
- 238000003860 storage Methods 0.000 description 2
- 230000008646 thermal stress Effects 0.000 description 2
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 2
- 229910052765 Lutetium Inorganic materials 0.000 description 1
- PWHULOQIROXLJO-UHFFFAOYSA-N Manganese Chemical compound [Mn] PWHULOQIROXLJO-UHFFFAOYSA-N 0.000 description 1
- 230000009471 action Effects 0.000 description 1
- 229910045601 alloy Inorganic materials 0.000 description 1
- 239000000956 alloy Substances 0.000 description 1
- 238000000137 annealing Methods 0.000 description 1
- 230000033228 biological regulation Effects 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
- 230000008878 coupling Effects 0.000 description 1
- 230000001808 coupling effect Effects 0.000 description 1
- 238000010168 coupling process Methods 0.000 description 1
- 238000005859 coupling reaction Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 230000005684 electric field Effects 0.000 description 1
- 230000005621 ferroelectricity Effects 0.000 description 1
- 230000005484 gravity Effects 0.000 description 1
- 150000002367 halogens Chemical class 0.000 description 1
- 239000012212 insulator Substances 0.000 description 1
- 150000002500 ions Chemical class 0.000 description 1
- 229910052748 manganese Inorganic materials 0.000 description 1
- 239000011572 manganese Substances 0.000 description 1
- 239000000155 melt Substances 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 238000000465 moulding Methods 0.000 description 1
- NDLPOXTZKUMGOV-UHFFFAOYSA-N oxo(oxoferriooxy)iron hydrate Chemical compound O.O=[Fe]O[Fe]=O NDLPOXTZKUMGOV-UHFFFAOYSA-N 0.000 description 1
- 239000002245 particle Substances 0.000 description 1
- 229920000642 polymer Polymers 0.000 description 1
- 230000035882 stress Effects 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 230000009466 transformation Effects 0.000 description 1
- 230000007306 turnover Effects 0.000 description 1
Classifications
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- C—CHEMISTRY; METALLURGY
- C30—CRYSTAL GROWTH
- C30B—SINGLE-CRYSTAL GROWTH; UNIDIRECTIONAL SOLIDIFICATION OF EUTECTIC MATERIAL OR UNIDIRECTIONAL DEMIXING OF EUTECTOID MATERIAL; REFINING BY ZONE-MELTING OF MATERIAL; PRODUCTION OF A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; SINGLE CRYSTALS OR HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; AFTER-TREATMENT OF SINGLE CRYSTALS OR A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; APPARATUS THEREFOR
- C30B13/00—Single-crystal growth by zone-melting; Refining by zone-melting
-
- C—CHEMISTRY; METALLURGY
- C30—CRYSTAL GROWTH
- C30B—SINGLE-CRYSTAL GROWTH; UNIDIRECTIONAL SOLIDIFICATION OF EUTECTIC MATERIAL OR UNIDIRECTIONAL DEMIXING OF EUTECTOID MATERIAL; REFINING BY ZONE-MELTING OF MATERIAL; PRODUCTION OF A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; SINGLE CRYSTALS OR HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; AFTER-TREATMENT OF SINGLE CRYSTALS OR A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; APPARATUS THEREFOR
- C30B13/00—Single-crystal growth by zone-melting; Refining by zone-melting
- C30B13/28—Controlling or regulating
-
- C—CHEMISTRY; METALLURGY
- C30—CRYSTAL GROWTH
- C30B—SINGLE-CRYSTAL GROWTH; UNIDIRECTIONAL SOLIDIFICATION OF EUTECTIC MATERIAL OR UNIDIRECTIONAL DEMIXING OF EUTECTOID MATERIAL; REFINING BY ZONE-MELTING OF MATERIAL; PRODUCTION OF A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; SINGLE CRYSTALS OR HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; AFTER-TREATMENT OF SINGLE CRYSTALS OR A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; APPARATUS THEREFOR
- C30B29/00—Single crystals or homogeneous polycrystalline material with defined structure characterised by the material or by their shape
- C30B29/10—Inorganic compounds or compositions
- C30B29/16—Oxides
- C30B29/22—Complex oxides
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- Inorganic Chemistry (AREA)
- Crystals, And After-Treatments Of Crystals (AREA)
Abstract
The invention discloses an optical floating zone method for preparing hexagonal Yb x In 1‑x FeO 3 A method for growing single crystals. The method comprises the following steps: weighing iron oxide, ytterbium oxide and indium oxide as raw materials according to the stoichiometric ratio of elements, uniformly mixing the raw materials, and presintering the raw materials for 12-24 hours at 800-1200 ℃ to ensure that the raw materials initially react to form Yb x In 1‑x FeO 3 Without forming orthogonal phases; isostatic compaction is carried out on the pre-sintered material to obtain a raw material rod; sintering the raw material rod at 1000-1200 ℃ for 12-24 hours, and keeping the raw material rod in a horizontal state in the sintering process to obtain a seed crystal rod; taking the seed crystal rod as a blanking rod, taking the raw material rod as a feeding rod, and carrying out crystal growth; cooling after the crystal growth is finished to obtain the hexagonal structure Yb x In 1‑x FeO 3 And (3) single crystals.
Description
Technical Field
The invention belongs to the field of crystal growth, and in particular relates to an optical floating zone method for preparing hexagonal structure Yb x In 1-x FeO 3 A method for growing single crystals.
Background
Rare earth iron oxide RFeO 3 (R is rare earth element, also called rare earth orthoferrite) refers to iron oxide containing rare earth element, and is an antiferromagnetic insulator with unique magnetic, magneto-optical and magneto-electric interactions. In recent years, rare earth iron oxide has abundant physics and huge application potential, so that the rare earth iron oxide becomes one of the latest research hot spots in the fields of condensed state and material physics. Researchers find a plurality of novel physical phenomena in rare earth iron oxides, such as ultrafast optomagnetism, laser-induced ultrafast spin reorientation, terahertz magneton-polaron, dick cooperative coupling in magnetic interaction, multiferroic properties and the like, and promote the deep understanding of related physical problems. In addition, the rare earth iron oxide can control spin turnover through a method other than a magnetic field, such as an electric field, and is expected to be applied to the aspects of micro sensors, ultra-fast ultra-high density information storage and the like.
Under conventional conditions, RFeO of perovskite structure 3 Belongs to an orthorhombic system (the space group is Pbnm), is a nonpolar centrosymmetric structure, and does not exist room-temperature ferroelectric polarization. DyFeO 3 And GdFeO 3 Crystal due to R 3+ With Fe 3+ Exchange shrinkage, with magneto-electric coupling effect at very low temperatures. RFeO 3 The antiferromagnetic transformation temperature of the polymer is up to 620-750K, so long as a stable polar non-central symmetrical structure can be obtained through symmetry regulation, and the multiferroic property at room temperature can be realized. As a typical single-phase multiferroic material, hexagonal RMnO 3 (r=ho-Lu, Y, sc, space group P63 cm) is greater than 1200K, but its magnetic ordering temperature TN is usually less than 100K, and room temperature multiferroics cannot be obtained. Theoretical prediction of hexagonal RFeO 3 With hexagonal RMnO 3 The same polarity is not a central symmetry structure, so that the alloy has room temperature ferroelectricity. The 3d orbit of the iron ion has higher coulomb repulsion energy and is easier to form compared with the manganese ionIn the insulating state, the iron ions have stronger exchange effect and higher magnetic ordering temperature. Thus, hexagonal RFeO 3 Hopefully solve the RMnO 3 Leakage current and TN are too low. However, when the A-site ion radius is small (e.g., in 3+ ，Sc 3+ And Ga 3+ Etc.), ABO 3 The perovskite forms a three-party polar structure (the space group is R3 c) and can realize room-temperature ferroelectric polarization, and meanwhile, fe at the B site 3+ And the magnetic order at room temperature can be ensured. But this results in BO 6 Octahedral distortion is very large and high pressure conditions are typically required to synthesize.
Disclosure of Invention
In view of the above problems, the present invention aims to provide an optical floating zone method for preparing hexagonal Yb x In 1-x FeO 3 A method for growing single crystals. The method successfully prepares hexagonal structure Yb x In 1-x FeO 3 The surface finish, density and uniformity of the single crystal are excellent, and the single crystal has good crystallization quality.
Yb with hexagonal structure according to the invention x In 1-x FeO 3 The growth method of the single crystal comprises the following steps:
step A: weighing iron oxide, ytterbium oxide and indium oxide as raw materials according to the stoichiometric ratio of elements, uniformly mixing the raw materials, and presintering the raw materials for 12-24 hours at 800-1200 ℃ to ensure that the raw materials initially react to form Yb x In 1-x FeO 3 Without forming orthogonal phases;
and (B) step (B): isostatic compaction is carried out on the pre-sintered material to obtain a raw material rod; sintering the raw material rod at 1000-1200 ℃ for 12-24 hours, and keeping the raw material rod in a horizontal state in the sintering process to obtain a seed crystal rod;
step C: taking a seed crystal rod as a blanking rod, taking a raw material rod as a feeding rod, keeping the rotation directions of the feeding rod and the blanking rod opposite, butting the feeding rod and the blanking rod after the feeding rod and the blanking rod are melted, and observing the stability of a melting area;
step D: starting a lifting system after the melting zone is stabilized, controlling the descending speed of a feeding rod to be 1-5mm/h, and controlling the descending speed of a discharging rod to be 0.5-4.5mm/h so as to control the growth speed of crystals to be 1-5mm/h for crystal growth;
step E: after the crystal growth is finished, the temperature is reduced by 0.5-2V/h for 10-24h in the first stage, the temperature is reduced by 2-5V/h for 10-24h in the second stage, and the temperature is reduced by 5-15V/h to room temperature in the third stage, so as to obtain the hexagonal Yb structure x In 1-x FeO 3 And (3) single crystals.
Preferably, 0.1.ltoreq.x.ltoreq.0.7.
Preferably, the growth rate of the crystals is 1-3mm/h.
Preferably, the temperature of the pre-sintering is 800-1000 ℃.
Preferably, ytterbium oxide is previously dried at 300-600 ℃ for 8-10 hours before use.
Preferably, step D is performed under a growing atmosphere of oxygen at a flow rate of 0.1-5L/min.
Preferably, the presintered material is ball-milled before molding, the mass ratio of the grinding balls to the material is 1:1-3:1, the ball milling rotating speed is 300-400r/min, and the ball milling time is 5-10h.
Preferably, the rotating speed of the feeding rod and the discharging rod is 8-20r/min.
Preferably, the Yb x In 1-x FeO 3 The diameter of the single crystal is 4-6mm, and the length is 30-60mm.
Drawings
FIG. 1 shows Yb prepared in example 1 0.6 In 0.4 FeO 3 Single crystal sample plot.
FIG. 2 shows Yb prepared in each example x In 1-x FeO 3 XRD pattern of single crystal.
Detailed Description
The invention is further illustrated by the following embodiments, which are to be understood as merely illustrative of the invention and not limiting thereof. Unless otherwise specified, each percentage refers to a mass percent.
The invention relates to the field of growth research of rare earth ferrite functional crystals, and mainly provides an optical floating zone method for preparing hexagonal Yb x In 1-x FeO 3 A method for growing single crystals. Rare earth ferrites are typically orthonormalThe perovskite structure of (2) and the hexagonal structure is metastable. RFeO at room temperature 3 Is an orthogonal phase. Therefore, when preparing the rare earth ferrite with a hexagonal structure, the pure hexagonal phase needs to be synthesized as much as possible in the material pretreatment process, and then the proper feeding speed, atmosphere speed and rotation speed are determined in the growth process, so that the stability of a melting zone is ensured, and the structural phase change caused by the fluctuation of the melting zone is prevented. Finally, after growing the hexagonal structure single crystal, the cooling rate of the melting zone needs to be reasonably adjusted, so that the smooth cooling zone is ensured to reach the room temperature, and the problems of crystal cracking and the like are prevented. The invention is hexagonal Yb x In 1-x FeO 3 Single crystal growth provides an efficient method of growth.
The growing method of the invention takes high-purity ferric oxide, ytterbium oxide and indium oxide as raw materials, obtains a polycrystal material rod with a hexagonal structure through ball milling, sintering, isostatic pressing and other processes according to chemical proportion, and then places the polycrystal material rod into a four-lamp light floating zone furnace for growing in oxygen atmosphere. Yb grown by the method x In 1-x FeO 3 The monocrystal has hexagonal structure and high crystallization quality.
The following specifically shows the preparation of hexagonal Yb by the optical floating zone method x In 1-x FeO 3 Detailed process steps of the method for growing single crystals.
And (5) pretreatment of raw materials. The pretreatment aims to fully and uniformly mix different raw materials, so that the raw materials initially react and remove impurities such as water possibly existing in the raw materials. Calculating according to the stoichiometric ratio of elements of the required raw materials to obtain the mass ratio of each component, and respectively and accurately weighing YbO 3 、InO 3 And FeO 3 . The raw materials are fully mixed and then put into a ball mill for ball milling. The specific process parameters of the ball mill can be adaptively changed according to the requirements. In some embodiments, the ball milling speed is 300-400r/min and the ball milling time is 5-10h. The mass ratio of grinding balls to material can also be adapted accordingly, for example 1:1 or 2:1 or 3:1. Pre-sintering the uniformly mixed raw materials in a muffle furnace at 800-1200 ℃ for 12-24h, naturally cooling to room temperature along with the furnace, and completing the pre-sintering of the polycrystalline raw materialsAnd (3) a treatment process. Preferably, the pre-sintering temperature is 800-1000 ℃. The purpose of the presintering is to cause the raw materials to initially react to form hexagonal Yb x In 1-x FeO 3 Without forming orthogonal phases. The muffle furnace is preferably used for horizontal sintering rather than vertical sintering, because the overall shape and uniformity of the material rod can be influenced under the action of gravity during vertical sintering, which is unfavorable for obtaining the hexagonal Yb x In 1-x FeO 3 And (3) single crystals.
YbO 3 、InO 3 And FeO 3 Preferably, a high purity raw material is used. Wherein, high purity YbO 3 Before use, the material is sintered for 8-10 hours at 300-600 ℃ in advance, so that possible impurities such as water in the air introduced in the storage process of the material are removed.
Preparing a polycrystal material rod. Fully grinding the pre-sintered polycrystalline raw material by an agate mortar, putting the ground polycrystalline raw material into a die, and performing isostatic compaction under the pressure of 40-300MPa to prepare a raw material rod. In some embodiments, the feedstock bar has a diameter of 6-10mm and a length of 80-100mm. Sintering the raw material rod in a muffle furnace at 1000-1200 ℃ for 12-24h, and cooling along with the furnace. The purpose of sintering is to allow the raw materials to react well to completion. The steps are repeated twice, and high-quality Yb is finally obtained x In 1-x FeO 3 A rod (which may also be referred to as a seed rod).
And (5) growing single crystals. The crystal growth can be carried out by adopting a four-halogen lamp through an optical floating zone furnace growth system focused by 4 ellipsoidal reflectors, and the heating temperature can reach 3000 ℃. And adjusting an optical system of the equipment to uniformly heat the focused heating light spots. The seed rod is fixed on a seat of the seed rod to be used as a blanking rod, the raw material rod is hung on a hook of the material rod to be used as a feeding rod, and the positions of the feeding rod and the blanking rod are adjusted to keep the vertical direction coaxial without obvious swing. And starting a rotating system, and keeping the rotating directions of the feeding rod and the discharging rod opposite, wherein the rotating speed is 8-20rpm. The growth atmosphere is oxygen, and the flow rate is controlled to be 0.1-5L/min. The oxygen atmosphere is introduced to protect the sample.
And starting a heating system, forming a narrower melting zone at a focus, butting the upper and lower material rods after the upper and lower material rods are melted, observing the stability of the melting zone, and starting a lifting system when the melting zone is stable. The descending speed of the feeding rod is controlled to be 1-5mm/h, and the descending speed of the corresponding discharging rod is controlled to be 0.5-4.5mm/h, namely, the crystal growth speed is controlled to be 1-5mm/h.
After the crystal growth is finished, cooling the crystal to room temperature by adopting sectional cooling, and annealing in an optical floating zone furnace to prevent structural phase change and crystal cracking caused by overlarge temperature change. The first stage is cooled by 0.5-2V/h for 10-24h, the second stage is cooled by 2-5V/h for 10-24h, and finally cooled by 5-15V/h to room temperature. The staged cooling can slowly relieve stress to avoid crystal cracking. Too fast a cooling down can also lead to crystal cracking.
In some embodiments, the following process parameters are employed: the growth speed of the crystal is 1-3mm/h; the counterclockwise rotation speed of the feeding rod is 10rpm, the clockwise rotation speed of the discharging rod is 10rpm, and the flow rate of the oxygen atmosphere is 1L/min.
The invention successfully carries out hexagonal Yb structure by adopting an optical floating zone method x In 1-x FeO 3 The single crystal grows, and the grown crystal has high crystallization quality, thus providing reference for the growth of the rare earth ferrite with hexagonal structure. In some examples, the Yb x In 1-x FeO 3 The single crystal is hexagonal, has a diameter of 4-6mm and a length of 30-60mm.
The present invention will be further illustrated by the following examples. It is also to be understood that the following examples are given solely for the purpose of illustration and are not to be construed as limitations upon the scope of the invention, since numerous insubstantial modifications and variations will now occur to those skilled in the art in light of the foregoing disclosure. The specific process parameters and the like described below are also merely examples of suitable ranges, i.e., one skilled in the art can make a suitable selection from the description herein and are not intended to be limited to the specific values described below.
Example 1
Hexagonal Yb structure 0.6 In 0.4 FeO 3 Preparation of single crystals
A. And (5) pretreatment of raw materials. High purity YbO 3 (3N or more) at 600 ℃ in advanceSintering for 10h according to Yb 2 O 3 ：In 2 O 3 ：Fe 2 O 3 The component mass ratio of the raw materials is calculated by the element series ratio with the molar ratio of 3:2:5, and Yb is respectively and accurately weighed 2 O 3 、In 2 O 3 And Fe (Fe) 2 O 3 . The raw materials are fully mixed and then put into a ball mill, the ball-material ratio is 2:1, the rotating speed is 400r/min, and the ball milling time is 5 hours. And (3) placing the raw materials subjected to ball milling and uniform mixing in a muffle furnace, sintering for 12 hours at the temperature of 1000 ℃, and naturally cooling to room temperature along with the furnace.
B. Preparing a polycrystal material rod. Fully grinding the pre-sintered polycrystalline raw material in the step A by an agate mortar, putting into a mould, isostatic pressing under the pressure of 80MPa to prepare a raw material rod with the diameter of 8mm and the length of 90mm, sintering in a muffle furnace at the temperature of 1200 ℃ for 24 hours, and naturally cooling to room temperature along with the furnace. The steps are repeated twice, and high-quality Yb is finally obtained 0.6 In 0.4 FeO 3 The material bars are seed crystal bars and raw material bars respectively.
C. And (5) growing single crystals. The crystal growth is carried out by adopting a four-halogen lamp through an optical floating zone furnace growth system focused by 4 ellipsoidal reflectors, and the heating temperature can reach 3000 ℃. And adjusting an optical system of the equipment to uniformly heat the focused heating light spots. And B, fixing the seed rod prepared in the step B on a table of a seed rod to serve as a blanking rod, hanging the raw material rod prepared in the step B on a hook of an upper fabric rod to serve as a feeding rod, and adjusting the positions of the feeding rod and the blanking rod to enable the feeding rod and the blanking rod to be coaxial in the vertical direction without obvious swing. And starting a rotating system, and keeping the rotating directions of the feeding rod and the discharging rod opposite, wherein the rotating speed is 10rpm. The growth atmosphere is oxygen, and the oxygen flow speed is controlled at 1L/min in the growth process. Starting a heating system, forming a narrower melting zone at a focus, after a feeding rod and a discharging rod are melted, butting the feeding rod and the discharging rod, observing the stability of the melting zone, starting a lifting system when the melting zone is stable, controlling the descending speed of the feeding rod to be 2.1mm/h, controlling the descending speed of the corresponding discharging rod to be 2mm/h, cooling the crystal to room temperature by adopting sectional cooling after the crystal growth is finished, cooling the voltage at 0.5V/h for 10h in the first stage, cooling at 5V/h for 10h in the second stage, and cooling at 15V/h to room temperature finally.
Hexagonal structure Yb obtained by the method 0.6 In 0.4 FeO 3 The length of the monocrystal is 40mm, the diameter is 5mm, the surface of the crystal is uniform and smooth, the crystallization condition of the crystal is good, no crack exists, and the structure is complete.
Example 2
Hexagonal Yb structure 0.6 In 0.4 FeO 3 Preparation of single crystals
A. And (5) pretreatment of raw materials. High purity YbO 3 (3N or more) is sintered in advance at 600 ℃ for 10 hours according to Yb 2 O 3 ：In 2 O 3 ：Fe 2 O 3 The component mass ratio of the raw materials is calculated by the element series ratio with the molar ratio of 3:2:5, and Yb is respectively and accurately weighed 2 O 3 、In 2 O 3 And Fe (Fe) 2 O 3 . The raw materials are fully mixed and then put into a ball mill, the ball-material ratio is 3:1, the rotating speed is 400r/min, and the ball milling time is 5 hours. And (3) placing the raw materials subjected to ball milling and uniform mixing in a muffle furnace, sintering for 12 hours at the temperature of 1000 ℃, and naturally cooling to room temperature along with the furnace.
B. Preparing a polycrystal material rod. Fully grinding the pre-sintered polycrystalline raw material in the step A by an agate mortar, putting into a mould, isostatic pressing under 100MPa pressure to prepare a raw material rod with the diameter of 8mm and the length of 90mm, sintering in a muffle furnace at 1200 ℃ for 12h, and naturally cooling to room temperature along with the furnace. The steps are repeated twice, and high-quality Yb is finally obtained 0.6 In 0.4 FeO 3 The material bars are seed crystal bars and raw material bars respectively.
C. And (5) growing single crystals. The crystal growth is carried out by adopting a four-halogen lamp through an optical floating zone furnace growth system focused by 4 ellipsoidal reflectors, and the heating temperature can reach 3000 ℃. And adjusting an optical system of the equipment to uniformly heat the focused heating light spots. And B, fixing the seed rod prepared in the step B on a table of a seed rod to serve as a blanking rod, hanging the raw material rod prepared in the step B on a hook of an upper fabric rod to serve as a feeding rod, and adjusting the positions of the feeding rod and the blanking rod to enable the feeding rod and the blanking rod to be coaxial in the vertical direction without obvious swing. And starting a rotating system, and keeping the rotating directions of the feeding rod and the discharging rod opposite, wherein the rotating speed is 20rpm. The growth atmosphere isOxygen, during the growth process, the oxygen flow speed is controlled at 1L/min. Starting a heating system, forming a narrower melting zone at a focus, after a feeding rod and a discharging rod are melted, butting the feeding rod and the discharging rod, observing the stability of the melting zone, starting a lifting system when the melting zone is stable, controlling the descending speed of the feeding rod to be 3mm/h, controlling the descending speed of the corresponding discharging rod to be 2.5mm/h, cooling the crystal to room temperature by adopting sectional cooling after the crystal grows, cooling the crystal to the room temperature at 0.5V/h in the first stage, cooling the crystal for 24h at 5V/h in the second stage, and cooling the crystal to the room temperature at 15V/h in the last stage. Hexagonal structure Yb obtained by the method 0.6 In 0.4 FeO 3 The length of the monocrystal is 35mm, the diameter is 4.8mm, the surface of the crystal is uniform and smooth, the crystallization condition of the crystal is good, no crack exists, and the structure is complete.
Example 3
Hexagonal Yb structure 0.5 In 0.5 FeO 3 Preparation of single crystals
A. And (5) pretreatment of raw materials. High purity YbO 3 (3N or more) is sintered in advance at 600 ℃ for 10 hours according to Yb 2 O 3 ：In 2 O 3 ：Fe 2 O 3 The component mass ratio of the raw materials is calculated by the element series ratio with the molar ratio of 5:5:10, and Yb is respectively and accurately weighed 2 O 3 、In 2 O 3 And Fe (Fe) 2 O 3 . The raw materials are fully mixed and then put into a ball mill, the ball-material ratio is 3:1, the rotating speed is 400r/min, and the ball milling time is 5 hours. And (3) placing the raw materials subjected to ball milling and uniform mixing in a muffle furnace, sintering for 12 hours at the temperature of 1000 ℃, and naturally cooling to room temperature along with the furnace.
B. Preparing a polycrystal material rod. Fully grinding the pre-sintered polycrystalline raw material in the step A by an agate mortar, putting into a mould, isostatic pressing under 100MPa pressure to prepare a raw material rod with the diameter of 8mm and the length of 90mm, sintering in a muffle furnace at 1200 ℃ for 12h, and naturally cooling to room temperature along with the furnace. The steps are repeated twice, and high-quality Yb is finally obtained 0.7 In 0.3 FeO 3 The material bars are seed crystal bars and raw material bars respectively.
C. And (5) growing single crystals. Crystal growth by four halogen lamps through 4 ellipsoidal reflector focused optical float zone furnace growth systemGrowing, and heating to 3000 deg.c. And adjusting an optical system of the equipment to uniformly heat the focused heating light spots. And B, fixing the seed rod prepared in the step B on a table of a seed rod to serve as a blanking rod, hanging the raw material rod prepared in the step B on a hook of an upper fabric rod to serve as a feeding rod, and adjusting the positions of the feeding rod and the blanking rod to enable the feeding rod and the blanking rod to be coaxial in the vertical direction without obvious swing. And starting a rotating system, and keeping the rotating directions of the feeding rod and the discharging rod opposite, wherein the rotating speed is 20rpm. The growth atmosphere is oxygen, and the oxygen flow speed is controlled at 1L/min in the growth process. Starting a heating system, forming a narrower melting zone at a focus, after a feeding rod and a discharging rod are melted, butting the feeding rod and the discharging rod, observing the stability of the melting zone, starting a lifting system when the melting zone is stable, controlling the descending speed of the feeding rod to be 3mm/h, controlling the descending speed of the corresponding discharging rod to be 2.5mm/h, cooling the crystal to room temperature by adopting sectional cooling after the crystal grows, cooling the crystal to the room temperature at 0.5V/h in the first stage, cooling the crystal for 24h at 5V/h in the second stage, and cooling the crystal to the room temperature at 15V/h in the last stage. Hexagonal structure Yb obtained by the method 0.5 In 0.5 FeO 3 The length of the monocrystal is 30mm, the diameter is 5.1mm, the surface of the crystal is uniform and smooth, the crystallization condition of the crystal is good, no crack exists, and the structure is complete.
Examples 4 to 10
Substantially the same as in example 1 except that Yb was changed 2 O 3 ：In 2 O 3 ：Fe 2 O 3 Molar ratio to Yb preparation 0.1 In 0.9 FeO 3 ,Yb 0.2 In 0.8 FeO 3 ,Yb 0.3 In 0.7 FeO 3 ,Yb 0.4 In 0.6 FeO 3 ,Yb 0.7 In 0.3 FeO 3 ,Yb 0.8 In 0.2 FeO,Yb 0.9 In 0.1 FeO 3 。
FIG. 2 shows Yb prepared in each example x In 1-x FeO 3 XRD pattern of single crystal. The phase of each sample was found to be hexagonal in comparison to the standard card.
Comparative example 1
Yb of orthogonal structure 0.6 In 0.4 FeO 3 Single crystalsPreparation
A. And (5) pretreatment of raw materials. High purity YbO 3 (3N or more) is sintered in advance at 600 ℃ for 10 hours according to Yb 2 O 3 ：In 2 O 3 ：Fe 2 O 3 The component mass ratio of the raw materials is calculated by the element series ratio with the molar ratio of 6:4:10, and Yb is respectively and accurately weighed 2 O 3 、In 2 O 3 And Fe (Fe) 2 O 3 . The raw materials are fully mixed and then put into a ball mill, the ball-material ratio is 3:1, the rotating speed is 400r/min, and the ball milling time is 5 hours. And (3) placing the raw materials subjected to ball milling and uniform mixing in a muffle furnace, sintering for 12 hours at the temperature of 1000 ℃, and naturally cooling to room temperature along with the furnace.
B. Preparing a polycrystal material rod. Fully grinding the pre-sintered polycrystalline raw material in the step A by an agate mortar, putting into a mould, isostatic pressing under 100MPa pressure to prepare a raw material rod with the diameter of 8mm and the length of 90mm, sintering in a muffle furnace at 1200 ℃ for 12h, and naturally cooling to room temperature along with the furnace. The steps are repeated twice, and high-quality Yb is finally obtained 0.7 In 0.3 FeO 3 The material bars are seed crystal bars and raw material bars respectively.
And (5) growing single crystals. The crystal growth is carried out by adopting a four-halogen lamp through an optical floating zone furnace growth system focused by 4 ellipsoidal reflectors, and the heating temperature can reach 3000 ℃. And adjusting an optical system of the equipment to uniformly heat the focused heating light spots. And B, fixing the seed rod prepared in the step B on a table of a seed rod to serve as a blanking rod, hanging the raw material rod prepared in the step B on a hook of an upper fabric rod to serve as a feeding rod, and adjusting the positions of the feeding rod and the blanking rod to enable the feeding rod and the blanking rod to be coaxial in the vertical direction without obvious swing. And starting a rotating system, and keeping the rotating directions of the feeding rod and the discharging rod opposite, wherein the rotating speed is 20rpm. The growth atmosphere is oxygen, and the oxygen flow speed is controlled at 1L/min in the growth process. Starting a heating system, forming a narrower melting zone at a focus, butting a feeding rod and a discharging rod after melting, observing the stability of the melting zone, starting a lifting system when the melting zone is stable, controlling the descending speed of the feeding rod to be 5mm/h, controlling the descending speed of the corresponding discharging rod to be 4.8mm/h, and cooling the voltage to room temperature at 1V/h after crystal growth is finished. By a means ofThe method obtains Yb with orthogonal structure 0.6 In 0.4 FeO 3 And (3) single crystals.
After the completion, the temperature is reduced by one step, so that the fluctuation of a melting area in the growth process is relatively large, and the thermal stress is not completely released, so that the hexagonal structure is changed into an orthogonal structure. Moreover, the surface of the crystal is cracked due to unreleased thermal stress, and partial polycrystal is generated inside.
Comparative example 2
Compared with example 1, the only difference is that:
and (5) pretreatment of raw materials. High purity YbO 3 (3N or more) is sintered in advance at 600 ℃ for 10 hours according to Yb 2 O 3 ：In 2 O 3 ：Fe 2 O 3 The component mass ratio of the raw materials is calculated by the element series ratio with the molar ratio of 3:2:5, and Yb is respectively and accurately weighed 2 O 3 、In 2 O 3 And Fe (Fe) 2 O 3 . The raw materials are fully mixed and then put into a ball mill, the ball-material ratio is 2:1, the rotating speed is 400r/min, and the ball milling time is 5 hours. And (3) placing the raw materials subjected to ball milling and uniform mixing in a muffle furnace, sintering for 24 hours at 1400 ℃, and naturally cooling to room temperature along with the furnace.
This comparative example shows cracking during the crystal preparation. This is because the presintering temperature is too high, resulting in the reaction of the raw materials to form the orthorhombic phase. And the hardness of the material with the orthogonal phase is relatively high, so that the material is difficult to sufficiently grind in the subsequent ball milling process. This results in small particle drop in the melt during growth, resulting in crystal cracking.
Comparative example 3
Compared with example 1, the only difference is that: the descending speed of the feeding rod is controlled to be 0.5mm/h, and the descending speed of the corresponding discharging rod is controlled to be 0.4mm/h.
The sample in this comparative example was not uniform in diameter and thickness. This is because the falling speed of the feeding rod and the discharging rod is slow, and the uniformity of the diameter of the grown sample is poor due to fluctuation of the melting zone.
Claims (9)
1. Preparation of hexagonal Yb structure by optical floating zone method x In 1-x FeO 3 A method for growing a single crystal, characterized in that the method comprisesThe method comprises the following steps:
step A: weighing iron oxide, ytterbium oxide and indium oxide as raw materials according to the stoichiometric ratio of elements, uniformly mixing the raw materials, and presintering the raw materials for 12-24 hours at 800-1200 ℃ to ensure that the raw materials initially react to form Yb x In 1-x FeO 3 Without forming orthogonal phases;
and (B) step (B): isostatic compaction is carried out on the pre-sintered material to obtain a raw material rod; sintering the raw material rod at 1000-1200 ℃ for 12-24 hours, and keeping the raw material rod in a horizontal state in the sintering process to obtain a seed crystal rod;
step C: taking a seed crystal rod as a blanking rod, taking a raw material rod as a feeding rod, keeping the rotation directions of the feeding rod and the blanking rod opposite, butting the feeding rod and the blanking rod after the feeding rod and the blanking rod are melted, and observing the stability of a melting area;
step D: starting a lifting system after the melting zone is stabilized, controlling the descending speed of a feeding rod to be 1-5mm/h, and controlling the descending speed of a discharging rod to be 0.5-4.5mm/h so as to control the growth speed of crystals to be 1-5mm/h for crystal growth;
step E: after the crystal growth is finished, the temperature is reduced by 0.5-2V/h for 10-24h in the first stage, the temperature is reduced by 2-5V/h for 10-24h in the second stage, and the temperature is reduced by 5-15V/h to room temperature in the third stage, so as to obtain the hexagonal Yb structure x In 1-x FeO 3 And (3) single crystals.
2. The method of claim 1, wherein 0.1.ltoreq.x.ltoreq.0.7.
3. A growth method according to claim 1 or 2, characterized in that the growth rate of the crystal is 1-3mm/h.
4. A growth method according to any one of claims 1 to 3, wherein the pre-sintering temperature is 800-1000 ℃.
5. The growth method according to any one of claims 1 to 4, wherein ytterbium oxide is previously dried at 300-600 ℃ for 8-10 hours before use.
6. A growth method according to any one of claims 1 to 5, wherein step D is performed under a growth atmosphere of oxygen at a flow rate of 0.1-5L/min.
7. A growth method according to any one of claims 1 to 6, wherein the pre-sintered material is ball milled before shaping, the mass ratio of grinding balls to material is 1:1-3:1, the ball milling speed is 300-400r/min, and the ball milling time is 5-10h.
8. A growth method according to any one of claims 1 to 7, wherein the rotational speed of the feed bar and the discharge bar is 8-20r/min.
9. The growth method according to any one of claims 1 to 8, wherein the Yb x In 1-x FeO 3 The diameter of the single crystal is 4-6mm, and the length is 30-60mm.
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